1. Field of the Invention
The present invention relates to esters of aryl benzimidazole sulfonic acids and their use as sunscreens in cosmetic compositions. More particularly, the present invention relates to compositions having esters of phenyl benzimidazole sulfonic acids with C16 to C50 alcohols and/or siloxane derivatives.
2. Description of the Related Art
Increased stability and increased sun protection benefits and reduced level of sunscreen required for effective sun protection and other performance characteristics are desirable attributes in sun care, skin care, hair care and personal care and cosmetic products, compositions and preparations.
For example, water resistance is a much-desired quality amongst consumers of color cosmetics, lipsticks, eyelash mascara, insect repellents, sunscreen preparations and sunscreen and insect repellent combinations, jelly fish repellent, poison ivy, poison oak, and poison sumac protective compositions. Additionally, shine and gloss are much desired attributes in nail color and hair care preparations. Surface smoothening can be important in a shampoo, hair conditioner, styling mousse and other hair treatment preparation, and can provide superior wet and dry hair combing.
Thus, there is a need in consumer products and cosmetic industry for formulations that can enhance the effectiveness of the various active ingredients contained therein and can deliver multiple benefits, such as, increased water resistance, increased stability, improved permanence, and increased performance characteristics, such as, increased sun protection benefits and reduced level of sunscreen required for effective sun protection.
Aryl benzimidazole sulfonic acid sunscreens known in the art are insoluble organic acids that must be converted to the salt form to make them suitable for use in cosmetic formulation. The use of salts imposes great constraints on the ability of the cosmetic formulators to produce waterproof sunscreens with acceptable aesthetics. For example, the effectiveness of carbomers, as well as some waterproofing polymers such as Diglycol/CHDM/Isophthalates/SIP Copolymer, is diminished in the presence of various levels of salt.
In contrast, the present invention provides novel sulfonate esters that are soluble in oil, which are easy to use raw material for cosmetic compositions and provide greater substantivity.
In applications that involve skin contact, the large molecular configuration of the present invention allows the chromophore to remain on the surface of the skin where it is more effective due to its reduced solubility in water.
Known aryl benzimidazole sulfonic acids and their water-soluble salts are insoluble in organic solvent systems. As a result, they must be incorporated into the water phase of a sunscreen composition where they have the potential to be washed off from the skin upon perspiration or exposure to water.
Further, sunscreen esters commonly used employ lower carbon organic groups, such as, C8 groups. Sunscreens with lower carbon organic groups do not exhibit good water resistance or sweat resistance.
The present invention addresses the problems of permanence associated with sunscreen agents, while maintaining the high extinction coefficients of the parent molecule.
In addition, the conjugated structure of the present invention allows for resonance delocalization to occur, while keeping the UV absorbance in the desired range for sun protection.
U.S. Pat. No. 6,262,170 describes a composition having an insoluble swollen gel network of a silicone elastomer of MDTQ structural type.
U.S. Pat. No. 6,238,657 also uses elastomers to form oil in silicone emulsions.
U.S. Pat. No. 6,517,816 describes a metastable sunscreen water-in-oil emulsion composition having an inner discontinuous phase and an outer continuous phase. There is no mention of any composition that has aryl benzimidazole sulfonic acid esters.
The present invention is applicable to a variety of personal care products including, but not limited to skin care, hair care, personal care, and color cosmetics.